Filling apparatus for high-altitude balloons

ABSTRACT

High-altitude balloons and apparatuses for filling such high-altitude balloons are provided. As an example, an apparatus for filling a high-altitude balloon includes a tube extending through envelope material of the balloon is provided. The apparatus also includes a flange connected to a first end of the tube. The flange is connected to an interior surface of the balloon. A fitting is connected to a second end of the tube. The fitting is configured for attachment with an apparatus for filling the balloon with lift gas. In addition, methods of filling high-altitude balloons with lift gas and methods of manufacturing balloons are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/161,613, filed May 23, 2016, which is a continuation of is acontinuation of U.S. patent application Ser. No. 14/703,061, filed May4, 2015, now issued as U.S. Pat. No. 9,371,124, which is a continuationof U.S. patent application Ser. No. 14/249,841, filed Apr. 10, 2014, nowissued as U.S. Pat. No. 9,027,877, the disclosures of which areincorporated herein by reference.

BACKGROUND

Computing devices such as personal computers, laptop computers, tabletcomputers, cellular phones, and countless types of Internet-capabledevices are increasingly prevalent in numerous aspects of modem life. Assuch, the demand for data connectivity via the Internet, cellular datanetworks, and other such networks, is growing. However, there are manyareas of the world where data connectivity is still unavailable, or ifavailable, is unreliable and/or costly. Accordingly, additional networkinfrastructure is desirable.

Some systems may provide network access via a balloon network operatingin the stratosphere. Because of the various forces experienced by theseballoons during deployment and operation, there is a balancing of needsbetween flexibility and stability of materials. The balloons may be madeof an envelope material configured in sections or lobes to create a“pumpkin” or lobed balloon. The lobes are supported by a plurality oftendons.

Before a balloon can be deployed, its envelope must be inflated withlighter than air lift gas. Helium and hydrogen gases are twoalternatives for lighter and air lift gases. Helium is an inert gas andthus considered generally safe. With helium, filling features can besealed with O-rings, check vales, or caps in a manual setting. As anexample, a person may remove a cap from a filling port, insert a fillinghose, pull out the filing hose, and cap the filling port. When thefilling hose is removed, gas can escape from the balloon. Eventraditional one-way valves may allow a small amount of gas to leak.Purging after closing the valve, but prior to disconnecting the fillline can prevent leaks, but adds additional complexity to the design.However, with helium prices on the rise and reduced availability,hydrogen is becoming a more economical option. However, as hydrogen ishighly explosive when combined with air, its use can present safetyissues, especially during inflation.

BRIEF SUMMARY

Aspects of the present disclosure are advantageous for providing a leakfree fill port that is also simple, robust and economical. For example,a high-altitude balloon including an apparatus for filling thehigh-altitude balloon is provided. The apparatus includes a tubeconfigured to extend through envelope material of the balloon. A flangeportion is connected to a first end of the tube. The flange portion isalso situated on an interior surface of the balloon. A fitting isconnected to a second end of the tube. The fitting is configured toattachment to an apparatus for filling the balloon with lift gas.

In one example, the tube is configured to be cold welded to seal thelift gas in the balloon. In another example, the flange portion includesa sealing O-ring configured to form a seal between the flange portionand the envelope material. In another example, high vacuum grease isapplied to the sealing O-ring. In another example, the flange portion isarranged as the base of a plug having threading, and wherein theapparatus further comprises a retaining nut having threading configuredto mate with the threading of the plug in order to secure the apparatusto the envelope material. In this example, the second end of the tubeincludes a second flange portion including at least one sealing O-ringconfigured to form a seal between the second flange portion and aninterior of the plug. In addition, the apparatus includes a cap portionconfigured to secure the second flange portion to the plug.

Other aspects of the disclosure provide a method of manufacturing ahigh-altitude balloon having a balloon envelope. The method includesinserting a tube through an opening in material of an incomplete balloonenvelope. The tube has a flange portion at a first end. The tube issecured to the incomplete balloon envelope. The incomplete balloonenvelope is then completed such that the flange portion and the surfaceof the material are located within a chamber of the completed balloonenvelope configured to receive lift gas.

In one example, the method also includes attaching a fitting to a secondend of the tube, the fitting being configured to attach to a fillingapparatus for filling the completed balloon envelope with the lift gas.In this example, attaching the fitting includes braze welding thefitting to the tube. In another example, the method also includes makingthe opening in the material. In another example, further securing thetube to the incomplete balloon envelope includes using an O-ring toclamp the balloon envelope material to the tube.

Further aspects of the disclosure provide a method of filling ahigh-altitude balloon with lift gas. The method includes connecting afilling apparatus to a fitting. The fitting is connected to a first endof a tube. The tube has a flange portion at a second end and isconnected to an envelope of the balloon. The method also includesfilling the envelope with the lift gas using the filling apparatus andpinching off the tube such that the tube is separated from the fillingapparatus.

In one example, the pinching off is a cold welding process which reducesa likelihood of combustion of the lift gas. In another example, thewelding prevents the lift gas from escaping from the envelope after thefilling. In another example, the lift gas includes hydrogen.

Another aspect of the disclosure provides a method of manufacturing ahigh-altitude balloon having a balloon envelope and a filling port. Themethod includes placing a plug body having a flange portion and athreaded portion within an opening in material of an incomplete balloonenvelope such that the flange portion is situated on a first side of theincomplete balloon envelope and at least some of the threaded portion issituated on a second side of the incomplete balloon envelope; attachinga retaining nut to the plug body to secure the plug body to theincomplete balloon envelope; completing the incomplete balloon envelopesuch that the flange portion and the surface of the material are locatedwithin a chamber of the completed balloon envelope configured to receivelift gas and the plug body and retaining nut are arranged as the part ofthe filling port.

In one example, the method also includes attaching a sealing O-ring tothe plug body, the sealing O-ring being configured to form a sealbetween the flange portion and an interior of the plug body. In anotherexample, the method also includes attaching a cap portion to a secondflange portion at one end of a tube in order to secure the second flangeportion to the plug body. In this example, the method also includesattaching a fitting to a second end of the tube, the fitting beingconfigured to attach to a filling apparatus for filling the completedballoon envelope with the lift gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional diagram of a system in accordance with aspects ofthe disclosure.

FIG. 2 is an example of a balloon in accordance with aspects of thedisclosure.

FIG. 3 is an example of a pinch off tube in accordance with aspects ofthe disclosure.

FIG. 4 is an example of a filling apparatus in accordance with aspectsof the disclosure.

FIG. 5 is an example diagram of the filling apparatus of FIG. 4 and aportion of balloon envelope material in accordance with aspects of thedisclosure.

FIG. 6 is another example diagram of the filling apparatus of FIG. 4 anda portion of balloon envelope material in accordance with aspects of thedisclosure.

FIG. 7 is an example diagram of a completed balloon envelope, fillingapparatus, and lift gas fill source in accordance with aspects of thedisclosure.

FIG. 8 is an example diagram of a pinched off filling apparatus, acompleted balloon envelope, and lift gas fill source in accordance withaspects of the disclosure.

FIG. 9 is a flow diagram in accordance with aspects of the disclosure.

FIG. 10 is another flow diagram in accordance with aspects of thedisclosure.

FIG. 11 is an example of a pinch off tube assembly in accordance withaspects of the disclosure.

FIG. 12 is an example of a filling apparatus attached to a balloon capin accordance with aspects of the disclosure.

FIG. 13 is a cross sectional view of the filling apparatus of FIG. 12.

FIG. 14 is a side view of the cross sectional view of the fillingapparatus of FIG. 13.

FIG. 15 is an exploded view of the filling apparatus and balloon cap ofFIG. 12.

FIG. 16 is a close up view of a portion of the cross sectional view ofthe filling apparatus of FIG. 13.

FIG. 17 is another close up view of a portion of the cross sectionalview of the filling apparatus of FIG. 13.

FIG. 18 is another close up view of a portion of the cross sectionalview of the filling apparatus of FIG. 13.

FIG. 19 is a cross sectional view of the filling apparatus of FIG. 12after being sealed.

FIG. 20 is a flow diagram in accordance with aspects of the disclosure.

FIG. 21 is another flow diagram in accordance with aspects of thedisclosure.

DETAILED DESCRIPTION

The present disclosure generally relates to filling high altitudeballoons with gas. As discussed above, such balloons may need to befilled with lighter than air lift gasses such as helium or hydrogen. Ashelium becomes more expensive with lesser availability, hydrogen becomesa more attractive option. However, because hydrogen is flammable, it isimportant to have filling features which reduce the likelihood of gasescaping, which could cause serious damage or injury to persons.

In one aspect, the filling apparatus may include a pinch-off tube havinga threaded body and a flange portion or plate at one end and a fittingat the other end may be utilized. Pinch-off tubes are typically used toprovide hermetic and leak tight for vacuum and low pressureapplications.

Where the balloon is likely to be used for more long term flights, forexample weeks or months or more, even very slow leaks can reduce theeffectiveness of the balloon envelope. In such examples, the pinch-offtube may be attached to a cap and balloon envelope using a plurality ofseals in order to further reduce the likelihood of even such smallleaks. For instance, the filling apparatus may include a pinch off tubeattached to a fitting at one end as well as a plug, a fill port body, afill port body retaining nut, and a fill tube cap. When assembled,sealing O-rings may provide an air tight seal between the fillingapparatus and the balloon envelope.

As noted above, a fitting may be welded to an end of the pinch off tube,for example, using braze welding. The pinch-off tube may be positionedthrough a hole in the balloon envelope material. The balloon envelopematerial may be sealed together in a completed envelope and made readyfor filling. In some examples, high vacuum grease may be applied to anyO-ring seals before or after the balloon is sealed together.

To fill the balloon, the fitting may be connected to an apparatus forproviding filling gas such as hydrogen or helium. Once the filling iscompleted, the tubing may be cold welded shut by a scissor-like cutter.By doing so, there is no chance for the lift gas to escape and littlelikelihood of injury due when using a gas such as hydrogen. In addition,the cold welding does not need to be performed manually by a person, butmay be done automatically by another apparatus. The pinch-off tubeprovides a single use, simple, and nonmoving part that is reliable,economical, and safe when using flammable filler gasses such ashydrogen.

FIG. 1 depicts an example system 100 in which a high altitude balloonsas described above may be used. This example should not be considered aslimiting the scope of the disclosure or usefulness of the featuresdescribed herein. System 100 may be considered a “balloon network.” Inthis example, balloon network 100 includes a plurality of devices, suchas of high altitude balloons 102A-F as well as ground base stations 106and 112. Balloon network 100 may also include a plurality of additionaldevices, such as various computing devices (not shown) as discussed inmore detail below.

As shown, the devices of system 100 are configured to communicate withone another. As an example, the balloons may include free-space opticallinks 104 and/or radiofrequency (RF) links 114 in order to facilitateintra-balloon communications. In this way, balloons 102A-F maycollectively function as a mesh network for packet data communications.Further, at least some of balloons 102A-B may be configured for RFcommunications with ground-based stations 106 and 112 via respective RFlinks 108. Some balloons, such as balloon 102F, could be configured tocommunicate via optical link 110 with ground-based station 112.

As noted above, to transmit data to another balloon, a given balloon 102may be configured to transmit an optical signal via an optical link 104.In addition, the given balloon 102 may use one or more high-powerlight-emitting diodes (LEDs) to transmit an optical signal.Alternatively, some or all of the balloons may include laser systems forfree-space optical communications over the optical links 104. Othertypes of free-space optical communication are possible. Further, inorder to receive an optical signal from another balloon via an opticallink 104, a given balloon may include one or more optical receivers.

The balloons 102A-F may collectively function as a mesh network. Morespecifically, since balloons 102A-F may communicate with one anotherusing free-space optical links, the balloons may collectively functionas a free-space optical mesh network where each balloon may function asa node of the mesh network. As noted above, the balloons of balloonnetwork 100 may be high-altitude balloons, which are deployed in thestratosphere. As an example, the balloons may generally be configured tooperate at altitudes between 18 km and 25 km above the Earth's surfacein order to limit the balloon's exposure to high winds and interferencewith commercial airline flights. Additional aspects of the balloons arediscussed in greater detail below, with reference to FIG. 2.

FIG. 2 is an example high-altitude balloon 200, which may represent anyof the balloons of balloon network 100. As shown, the balloon 200includes an envelope 210, a payload 220 and a plurality of tendons230-250 attached to the envelope 210.

The high-altitude balloon envelope 210 may take various forms. In oneinstance, the balloon envelope 210 may be constructed from materialssuch as polyethylene that do not hold much load while the balloon 200 isfloating in the air during flight. Additionally, or alternatively, someor all of envelope 210 may be constructed from a highly flexible latexmaterial or rubber material such as chloroprene. Other materials orcombinations thereof may also be employed. Further, the shape and sizeof the envelope 210 may vary depending upon the particularimplementation. Additionally, the envelope 210 may be a chamber filledwith various gases or mixtures thereof, such as helium, hydrogen or anyother lighter-than-air gas, hereafter, lift gas. The envelope 210 isthus arranged to have an associated upward buoyancy force duringdeployment of the payload 220.

The payload 220 of balloon 200 is affixed to the envelope by aconnection 260 such as a cable. The payload 220 may include a computersystem (not shown), having one or more processors and on-board datastorage. The payload 220 may also include various other types ofequipment and systems (not shown) to provide a number of differentfunctions. For example, the payload 220 may include an opticalcommunication system, a navigation system, a positioning system, alighting system, an altitude control system and a power supply to supplypower to various components of balloon 200.

In view of the goal of making the balloon envelope 210 as lightweight aspossible, it may be comprised of a plurality of envelope lobes or goresthat have a thin film, such as polyethylene or polyethyleneterephthalate, which is lightweight, yet has suitable strengthproperties for use as a balloon envelope deployable in the stratosphere.In this example, balloon envelope 210 is comprised of envelope gores210A-210D.

The individual envelope gores 210A-210D may be shaped so that the lengthof the edge seam connecting adjacent envelope gores is greater than thelength of a centerline of the envelope gores. Thus, the envelope gores210A-210D may be shaped to better optimize the strain rate experiencedby the balloon envelope 210. The pressurized lifting gas within theballoon envelope 210 may cause a force or load to be applied to theballoon 200.

The tendons 230-250 provide strength to the balloon 200 to carrier theload created by the pressurized gas within the balloon envelope 210. Insome examples, a cage of tendons (not shown) may be created usingmultiple tendons that are attached vertically and horizontally. Eachtendon may be formed as a fiber load tape that is adhered to arespective envelope gore. Alternately, a tubular sleeve may be adheredto the respective envelopes with the tendon positioned within thetubular sleeve.

Top ends of the tendons 230, 240 and 250 may be coupled together usingan apparatus, such as top cap 201 positioned at the apex of balloonenvelope 210. Bottom ends of the tendons 230, 240 and 250 may also beconnected to one another. For example, a corresponding apparatus, e.g.,bottom cap 202, is disposed at a base or bottom of the balloon envelope210. The top cap 201 at the apex may be the same size and shape as andbottom cap 202 at the bottom. Both caps include corresponding componentsfor attaching the tendons 230, 240 and 250, and may be formed fromstainless steel or aluminum.

FIG. 3 is an example of a pinch-off tube 300 which may be used as a fillport for a high altitude balloon such as balloon 200. In this example,pinch-off tube 300 includes a tubular portion 302 having an open firstend 304 and an opposing open second end 306. The open second end 306 isshown in dashed line to indicate that it is with threaded body 312. Thethreaded body 312 has a diameter that is wider than the diameter of theopen first end 304 of the tubular portion. In this regard, pinch-offtube 300 includes a passageway such that air or other gasses may flowalong the general the path of arrows 308 from the open first end 304 tothe opposing open second end 306 and from the open second end 306 to theopen first end 304. The arrows 308 shown in dashed line indicate thatthey are within the tubular portion 302. The threaded body 312 isconnected to a flattened disc or flange portion 310. The pinch-off tube300, threaded body 312, and flange portion may be made of variousmetals, including, for example copper.

FIG. 4 is an example of a filling apparatus 400 that includes a fitting402 is attached to the open first end 304 of pinch-off tube 300. In thisregard, the fitting 402 may be fixed to the open first end 304 of thetubular portion 302 by braze welding or other connection techniquesprior to or after the filling apparatus 400 is attached to a balloonenvelope as described below. Fitting may be configured to connect thefilling apparatus 400 with a lift gas fill source in order to fill ahigh altitude balloon such as balloon 200 with lift gas.

The filling apparatus may be attached to a balloon envelope during themanufacturing of the balloon. For example, before the balloon envelopeis completed, a hole may be cut into a portion of the balloon envelopematerial. The filling apparatus may be placed through the hole from whatwill become the interior of the balloon envelope. In this regard, thesecond end of the filling apparatus having the fitting may be passedthrough the hole as well as the tubular portion of the pinch-off tube.Once the flange of the pinch-off tube is positioned below the hole, anut or other fixation device may be used further secure the balloonenvelope material to the filling apparatus and in particular, to thethreaded body of the pinch-off tube.

FIG. 5 is an example 500 of the filling apparatus 400 being positionedrelative to a portion of the balloon envelope material 502. In thisexample the second open end 306, flange 310, the tubular portion 302,and part of the fitting 402 are shown in dashed line as these featuresare located below the portion of envelope material 502 or what willbecome an interior of the balloon envelope. As noted above, after thefilling apparatus is secured to the portion of balloon envelope material502, the portion of the balloon envelope material may be one of envelopegores 210A-210D attached to other such envelope gores in order to form acompleted balloon envelope such as balloon envelope 210.

Hole 504 may be cut into the portion of balloon envelope material 502using any conventional cutting technique. Hole 504 may be sized suchthat the fitting 402 and tubular portion 302 may be passed through thehole. Hole 504 may be smaller than the area of flange 310 such that theflange cannot pass through hole 504, though larger holes may also beused.

In some examples, prior to inserting the filling apparatus 400 into thehole 504 or after the balloon envelope is completed, a high vacuumgrease may be applied to all or a portion of the filling apparatus.Fitting 402 is then passed through the hole from a side of the portionof balloon envelope material 502 that will become the interior of theballoon envelope 210 when the envelope is completed. Thus, in theexample of FIG. 500, fitting 402 is passed through the hole 504 in thedirection of arrow 506.

FIG. 6 is an example 600 of the filling apparatus 400 being secured to aportion of the balloon envelope material 502. Once the fitting 402passes through the hole 504 (as shown in FIG. 5), the tubular portion302 is also passed through the hole until at least a portion of thethreaded body 312 is through the hole and the flange 310 meets with theportion of balloon envelope material 502 as shown in FIG. 6. Thus, inthis example the second open end 306 and flange 310 are shown in dashedline as these features are located below the portion of envelopematerial 502 or what will become an interior of the balloon envelope.

In order to secure the pinch-off tube to the portion of balloonenvelope, a fixation device such as a nut may be used. A nut 606 may beplaced over the fitting 402 and moved down in the direction of arrow 608until the clamp is positioned around the gathered material. Nut 606includes an opening 610 wide enough to pass over the fitting 402. Theopening also includes threading 612 that is configured to mate with thethreading of the threaded body 312. The nut 606 may then be tightenedaround the threaded body 312 in order to secure the balloon envelopematerial to the filling apparatus, for example, by way of a clampingforce as is shown in example 700 of FIG. 7.

Once the filling apparatus is secured to the balloon envelope material,the balloon envelope and balloon may be completed. For example, as notedabove, the portion of balloon envelope material 502 may be secured toother such portions (though without the filling apparatus) using animpulse sealing process or other process in order to create a completedballoon envelope as shown in FIG. 2. The completed balloon envelope thusincludes a chamber for receiving lift gas. The balloon envelope may thenbe configured with the various other features discussed above in orderto produce a completed balloon.

The completed balloon may then be inflated using the filling apparatus.For example, the completed balloon envelope may then be attached to alift gas fill source via the fitting in order to fill the envelope withlift gas. Thus, lift gas may progress from the lift gas fill source,through the tubular portion, and into the balloon envelope in order toinflate the chamber of the balloon envelope. Once a desired level ofinflation has been reached, the filling apparatus may be pinched off,for example, using a cold welding process. For instance, while thefilling apparatus is still connected to the lift gas fill source, thetubular portion of the filling apparatus may be crushed by a scissorlike tool such as a pinch-off tool until the tubular portion is severedinto two sections. The section having the fitting may thus still beconnected to the lift gas fill source. This section may be discarded.The other section connected to the balloon envelope material may form anair tight chamber.

FIG. 7 is an example 700 of a completed balloon envelope 702 thatincludes the portion of balloon envelope material 502 having the fillingapparatus 400. Again, the second open end 306 and flange 310 are shownin dashed line as these features are located below the portion ofballoon envelope material 502 and on an interior of the completedballoon envelope 702.

In this example, the fitting 402 is connected to a lift gas fill source704. Lift gas fill source 704 may include a hose or other device thatprovides lift gasses such as hydrogen or helium to fill the completedballoon envelope 502. The hose may be configured to detachably mate withfitting 403, for example, via complementary threading. As such, tubularportion 302 connects an interior or chamber of the completed balloonenvelope 702 with the lift gas fill source 704. The tubular portion 302extends through a hole 406 in the portion of envelope material 402. Thenut 606 again secures the filling apparatus to the portion of balloonenvelope 502 and provides an air tight seal as the chamber is inflated.

In order to fill the balloon envelope, the lift gas fill source 704 maybe connected to fitting 410 of the filling apparatus 400 as shown inFIG. 7. The lift gas fill source 704 may then be used to provide liftgasses to inflate the completed balloon envelope 702. The lift gassesmay flow from the lift gas fill source 704 through the fitting 410, thetubular portion 302, and into a chamber of the completed balloonenvelope 702 along arrows 706.

Once a desired inflation of the completed balloon envelope 702 isreached, the tubular portion 302 may be pinched off. For example, ascissor like tool such as a pinch-off tool may be used to cold weld thetubular portion 302 by crushing the tubular portion 302 into twosections and forming a seal on each of the two sections. Example 800 ofFIG. 8 depicts two sections 302A and 302B of the tubular portion whichhave been severed from one another using a pinch-off tool at line 708(shown in FIG. 7). In this example, the tubular portion has been crushedsuch that each section 302A and 302B has an air tight seal 802A and802B, respectively. Section 302A which is still attached to lift gasfill source 704 via the fitting 410 may be removed from lift gas fillsource and discarded. Air tight seal 802A may prevent lift gasses fromescaping from the completed balloon envelope 702 during use of theballoon even in high-altitude environments as described above.

Flow diagram 900 of FIG. 9 is an example flow diagram of some of theaspects described above which may be used to manufacture a high-altitudeballoon having a balloon envelope. In this example, a tube is insertedthrough an opening in material of an incomplete balloon envelope atblock 902. The tube has a flange at a first end. The opening may be madein the material by cutting the material using an instrument having asharp blade or a punch tool. As noted above, a fitting may also beattached to a second end of the tube via braze welding. This fitting canbe configured to attach to a filling apparatus for filling a completedballoon envelope with lift gas. The tube secured to the incompleteballoon envelope at block 904. As an example, an O-ring clamp may beused to clamp the balloon envelope material to the tube. The incompleteballoon envelope is then completed such that the flange and the surfaceof the material are located within a chamber of the completed balloonenvelope configured to receive lift gas at block 906.

Flow diagram 1000 of FIG. 10 is an example flow diagram of some of theaspects described above which may be used to fill a high-altitudeballoon with lift gas. In this example, a filling apparatus is connectedto a fitting at block 1002. The fitting is connected to a first end of atube. The tube having a flange at a second end and being connected to anenvelope of the balloon. The envelope is filled with the lift gas usingthe filling apparatus at block 1004. As noted above, in some examples,the lift gas may include hydrogen. The tube is pinched off such that thetube is separated from the filling apparatus at block 1006. The pinchingoff may include a cold welding process which reduces a likelihood ofcombustion of the lift gas. The pinching off may also prevent the liftgas from escaping from the envelope after the filling.

Thus, the features described above allow no chance for the lift gas toescape after inflation but before the chamber of the completed balloonenvelope is sealed. This also reduces the likelihood of injury due whenusing a gas such as hydrogen. In addition, the cold welding does notneed to be performed manually by a person using a pinch-off tool, butmay be done automatically by another apparatus. The filling apparatustube provides a single use, simple, and nonmoving part that is reliable,economical, and safe when using flammable filler gasses such ashydrogen.

FIG. 11 is an example of a pinch-off tube assembly 1100 which may beused as a fill port for a high altitude balloon such as balloon 200. Inthis example, pinch-off tube assembly 1100 includes a tubular portion1102 having an open first end 1104 and an opposing open second end 1106.Pinch-off tube assembly 1100 includes a passageway such that air orother gasses may flow along the general the path of arrows 1108 from theopen first end 304 to the opposing open second end 1106 (more clearlyshown in FIG. 13) as well as from the open second end 306 to the openfirst end. Second end 1106 is connected to a disc or flange portion 1110of a plug 1112. The flange portion 1100 includes a lip 1114 that extendsoutwardly from the flange portion.

The tubular portion 1102 may include various metals, including, forexample copper. The tubular portion 1102 may be attached, for example bybraze welding, to the flange portion 1110. The plug 1112 (and the flangeportion 1110) may be made of materials different from the tubularportion 1102, such as stainless steel or aluminum.

The plug 1112 may also include one or more grooves (shown as grooves1116 and 1118 in FIG. 13). Sealing devices, such as O-rings 1126 and1128 may be placed in such grooves. The O-rings 1126 and 1128 may beformed of flouroscilicone or other flexible materials well suited to lowtemperature environments as described in more detail below.

FIGS. 12-14 are examples of a filling apparatus 1200 for filling aballoon envelope of a balloon, such as balloon 200, with lift gas. FIG.13 is a cross sectional view of FIG. 12, and FIG. 14 is an offset viewof the cross sectional view of FIG. 12. FIG. 15 is a break out view ofthe components of filling apparatus 1200.

Referring to FIGS. 12 and 15, in addition to the pinch-off tube assembly1100, the filling apparatus includes a fill port body 1202, a fill portbody retaining nut 1204, and a fill tube cap 1206. Each of the fill portbody 1202, the fill port body retaining nut 1204, and the fill tube cap1206 may be made of a crystallized plastic or high-performance acetalresin such as commercially available Delrin® products.

The fill port body 1202 includes a lower flange portion 1222 and athreaded body portion 1224 having threading. The lower flange portionhas grooves 1226 and 1228 separated by a thin flexure section 1230. Asealing device such as envelope sealing O-ring 1232 is situated in thegroove 1226. Envelope sealing O-ring may also be formed offlouroscilicone or other materials well suited to low temperatureenvironments. However, as described in more detail below, the envelopesealing O-ring 1232 may also be made of other materials without suchproperties. The fill port body 1202 may also include a passageway 1228that passes through the threaded body portion 1224 and the lower flangeportion 1222 in order to lift gas to pass from one end of the passagewayto the other.

The fill port body retaining nut 1204 includes internal threading 1240.The internal threading 1240 is complementary to threading of thethreaded body portion 1224 of the fill port body 1202. In this regard,the fill port body 1202 may be secured to a portion of the top cap 201and a portion of the envelope 210 (shown most clearly in FIG. 15) ofballoon 200 via the fill port retaining nut 1204 and envelope sealingO-ring 1232.

The fill tube cap 1206 includes internal threading 1260 that iscomplementary to the threading of the threaded body portion 1224. Thefill tube cap also includes a contact surface 1262 configured to contactthe lip 1114 of the flange portion 1110.

Filling apparatus 1200 may also include a fitting (not shown) attachedto the open first end 1104 of the pinch-off tube assembly 1100. Thisfitting may be configured similar to fitting 402 of FIG. 4. In thisregard, the fitting may be fixed to the open first end 1104 of thetubular portion 1102 by braze welding or other connection techniques.The fitting may be configured to connect the filling apparatus 1200 witha lift gas fill source in order to fill a high altitude balloon such asballoon 200 with lift gas.

FIG. 16 is a close up view of box 1300 of FIG. 13. Although not shown assuch, envelope sealing O-ring 1232 is compressed by the force of fillport body retaining nut 1204 on the top cap 201 and balloon envelope210. This compression force on the envelope sealing O-ring 1232 createsa seal between the balloon envelope 210, and the fill port body 1202. Inaddition, this force may also compress the thin flexure section 1230. Insome examples, this thin flexure section 1230 may be compressed as muchas the O-ring by the force of the fill port body retaining nut 1204 onthe top cap 201. For instance, the thin flexure section 1230 may have across section of approximately 0.125 in and may be compressed a distanceon the order of 0.015 in or more or less. The thing flexure section 1230may keep the O-ring in place at temperatures well below the O-ring'selastic temperature (e.g. at −50 degrees Celsius where the O-ring losesits elastic characteristics and becomes ridged) such that the seal ismaintained. Thus, the envelope sealing O-ring 1232 may be made ofmaterials other than flouroscilicone or other materials well suited tolow temperature environments.

FIG. 17 is a close up view of box 1310 of FIG. 13. Although not shown assuch, O-rings 1126 and 1128 compressed within the grooves 1116 and 1118,respectively, between the plug 1112 and an interior surface of fill portbody 1202. The minimum and maximum compression values may beapproximately 15 and 19 percent of the cross sectional width of the ring(measured though line 1802 of FIG. 18), respectively. The compressedO-rings each form a seal between the plug 1112 of the filling apparatus1100 and the fill port body retaining nut 1204. In this regard, only asingle O-ring may be required to provide a sufficient seal, however thesecond O-ring may provide for further protection against leaks shouldthe first O-ring fail.

As noted above, the low temperatures in the stratosphere can causevarious components of the filling apparatus 1200 to change shape. Forexample, the O-rings may lose their shape at −80 degrees Celsius,shrinking within the grooves a distance on the order of 0.001 of aninch. Similarly, the other components of the filling apparatus 1200 mayalso shrink. Such shrinkage may cause very small leaks in the balloonenvelope 210 which can allow lift gas to escape. As noted above, thiscan be problematic for long term (e.g. weeks or months or more) flightsin the stratosphere. The amount of shrinkage may be determined using thecoefficient of thermal expansion for each of the materials used in thefilling apparatus.

However, the seals between the filling apparatus 1100 and the fill portbody retaining nut 1204 may enable continuous seal contact well belowthe elastic temperature of the O-rings. For example, the materials anddimensions selected for the O-rings, fill port body, and plug may beselected such that the change in the cross sectional area of the groovesis equal to the change in the cross sectional area of the grooves. Table1 below provides example dimensions, materials, and coefficients ofthermal expansion (CTE) for such materials. Assuming zero elasticity ofthe O-ring material below −20 degrees Celsius, any movement would be dueto the thermal coefficient of expansion at or below this temperature.The combination of components in Table 1 provide for complementarychanges in the shapes of these components below −20 degrees Celsius,expected conditions in the stratosphere. In other words, the change inthe distance between the grooves and the fill port body is approximatelyequal to the change in the diameter of the O-ring thereby reducing thelikelihood of even small leaks around these O-rings during a flight inthe stratosphere.

TABLE 1 Example Dimensions, Materials and CTEs Component DimensionMaterial CTE O-rings 1106 0.139 ± 0.003 inch flouroscilicone  810 ppm/Kand 1108 diameter cross section of O-ring for a #244 O-ring (e.g.,measured through line 1802 of FIG. 18 when uncompressed and at SATP)Plug 1112 1.780 inch diameter 304 Stainless 17.3 ppm/K cross section atthe Steel grooves 1116 and 1118 (e.g., measured through line 1804 ofFIG. 18 when uncompressed and at SATP) Fill port body 2.007 inchdiameter Delrin ®  122 ppm/K 1202 interior cross section (e.g., measuredthrough line 1806 of FIG. 18 at SATP)

As with filling apparatus 300, filling apparatus 1200 may be attached toa balloon envelope during the manufacturing of the balloon. For example,before the balloon envelope is completed, a hole may be cut into aportion of the balloon envelope material using any conventional cuttingtechnique. In addition, a hole may be made in the cap, for exampleduring or after the material of the cap is form. These holes may bealigned with one another, and the various components of fillingapparatus 1200 may be connected to one another (as shown in FIGS. 13 and14.

Referring to FIG. 15, the balloon envelope 210 includes a hole 1502 andcap 201 includes hole 1504 which may be cut or formed as discussedabove. The size and shape of these holes generally corresponds to awidth of threaded body portion 1224 of the fill port body 1202 but areno larger than a diameter of the sealing o-ring 1232 and the lowerflange portion 1222.

In order to attach the filling apparatus 1200 to the balloon envelopeand cap, the hole 1502 in the balloon envelope 210 may be aligned withthe hole 1504 in the cap 201 as shown in FIG. 15. The threaded bodyportion 1224 of the fill port body 1202 is placed through the holes 1502and 1504 from what will become the interior of the balloon envelope 210.The lower flange portion 1222 does not pass through the holes 1502 and1504 but makes contact with what will become an interior surface of theballoon envelope 210.

The pinch-off tube assembly 1100 may then be placed within passageway1228 of the fill port body 1202 until lip 1114 contacts a top portion ofthe threaded body portion 1224. O-rings 1126 and 1128 are compressedwithin the grooves 1116 and 1118 and against an internal surface of thethreaded body portion 1224 as shown in FIGS. 13 and 14. In this regard,as noted above, O-rings 1126 and 1128 may each form an air tight sealwith the threaded body portion 1224.

Before or after the plug 1112 of pinch-off tube assembly 1100 is placedwithin passageway 1228, the fill port body retaining nut 1204 is thenplaced over the threaded body portion 1224. For example, the fill portbody retaining nut 1204 may be screwed onto the threaded body portionvia the complementary threading of internal threading 1240. As the fillport body retaining nut 1204 is tightened against the cap 201, sealingO-ring 1232 creates an air tight seal against what will become theinterior surface of the balloon envelope 210.

In order to further secure the pinch-off tube assembly 1100 to the fillport body 1202, the fill tube cap 1206 is placed over the tubularportion 1102 and onto the threaded body portion 1224 of the fill portbody 1202. The fill tube cap 1206 may be secured to the threaded bodyportion 1224 via internal threading 1260 and the threading of thethreaded body portion. The fill tube cap 1206 may also secure thepinch-off tube assembly 1100 in place by contact between surface 1262and the lip 1114 of the flange portion 1110.

Once the fill port body is secured to the balloon envelope material, theballoon envelope and balloon may be completed as described above inorder to produce a completed balloon. In this regard, the pinch-off tubeassembly 1100 may be secured to the fill port body before or after theballoon envelope and balloon are completed. In addition, in someexamples, before, during, and after assembly of the filling apparatus tothe balloon envelope and cap, high vacuum grease may be applied to allor some of the components of the filling apparatus 1200.

Once the filling apparatus and the completed balloon are assembled, thecompleted balloon may then be inflated using the filling apparatus 1200.As with the filling apparatus 400 and the example of FIG. 8, thecompleted balloon envelope and filling apparatus 1200 may then beattached to a lift gas fill source via the fitting (not shown) in orderto fill the envelope with lift gas. Thus, lift gas may progress from thelift gas fill source, through the passageways of the tubular portion andthe fill port body, and into the balloon envelope in order to inflatethe chamber of the balloon envelope. Again, the O-rings provide airtight seals in order to prevent gas from escaping during inflation.

Once a desired level of inflation has been reached, the fillingapparatus 1200 may be pinched off, for example, using a cold weldingprocess as described above. FIG. 19 is an example 1900 of fillingapparatus 1200 after it has been welded shut. In this example, the openend 1104 (not shown) has been removed from the filling apparatus 1200and an air tight seal 1902 is formed. As with the example of fillingapparatus 400, the section of the tubular portion 1102 associated withthe open end 1104 may be still attached to lift a gas fill source viathe fitting. This section may be removed from lift gas fill source anddiscarded. Air tight seal 1902 as well as the seals of each of theO-rings 1126, 1128, and 1226 may prevent lift gasses from escaping fromthe completed balloon envelope during use of the balloon even inhigh-altitude environments as described above.

Flow diagram 2000 of FIG. 20 is an example flow diagram of some of theaspects described above which may be used to manufacture a high-altitudeballoon having a balloon envelope using a filling apparatus such asfilling apparatus 1200. In this example, a fill port body is insertedthrough an opening in material of an incomplete balloon envelope and capat block 2002. The fill port body has a flange. The fill port body issecured to the incomplete balloon envelope and the cap at block 2004.The incomplete balloon envelope is then completed such that the flangeand the surface of the material are located within a chamber of thecompleted balloon envelope configured to receive lift gas at block 2006.A pinch-off tube assembly is attached to the fill port body at block2008. Again, as noted above, the pinch-off tube assembly may be attachedbefore or after the incomplete balloon envelope is completed.

Flow diagram 2100 of FIG. 21 is an example flow diagram of some of theaspects described above which may be used to fill a high-altitudeballoon with lift gas. In this example, a filling apparatus is connectedto a fitting at block 2102. The fitting is connected to a first end of atube. The filling apparatus is connected to a balloon envelope and a capportion of a balloon. The envelope is filled with the lift gas using thefilling apparatus at block 2104. As noted above, in some examples, thelift gas may include hydrogen. The tube is pinched off such that thetube is separated from the filling apparatus at block 2106. The pinchingoff may include a cold welding process which reduces a likelihood ofcombustion of the lift gas. The welding may also prevent the lift gasfrom escaping from the envelope after the filling.

Unless otherwise stated, the foregoing alternative examples are notmutually exclusive, but may be implemented in various combinations toachieve unique advantages. As these and other variations andcombinations of the features discussed above can be utilized withoutdeparting from the subject matter defined by the claims, the foregoingdescription of the embodiments should be taken by way of illustrationrather than by way of limitation of the subject matter defined by theclaims. In addition, the provision of the examples described herein, aswell as clauses phrased as “such as,” “including” and the like, shouldnot be interpreted as limiting the subject matter of the claims to thespecific examples; rather, the examples are intended to illustrate onlyone of many possible embodiments. Further, the same reference numbers indifferent drawings can identify the same or similar elements.

The invention claimed is:
 1. A system comprising: a filling apparatusfor filling a balloon, the apparatus comprising: a tube having a firstend and a second end; and a plug member connected to the second end suchthat the tube extends through at least a portion of the plug member toprovide a conduit for gas between the first end and a second end andthrough the plug, the plug member having a flange portion arrangedaround the tube, and the plug member further having at least one groovearranged around an external surface of the plug member; and an o-ringarranged in the at least one groove.
 2. The system of claim 1, whereinthe flange portion corresponds to a disc with a lip that extendsoutwardly relative to a surface of the plug member in which the at leastone groove is arranged.
 3. The system of claim 1, wherein the tube iscomprised of a first metal and the plug member is comprised of a secondmetal.
 4. The system of claim 3, wherein the tube is comprised ofcopper.
 5. The system of claim 3, wherein the plug member is comprisedof stainless steel.
 6. The system of claim 3, wherein the first metal isdifferent from the second metal.
 7. The system of claim 1, wherein thematerials of the o-ring and plug member are selected to compensate forchanging dimensions of the materials at predetermined temperatures. 8.The system of claim 1, wherein the tube is configured for cold weldingto seal lift gas in the balloon.
 9. The system of claim 1, wherein theplug member includes a second groove arranged between the first grooveand the flange.
 10. The system of claim 8, further comprising a secondO-ring arranged in the second groove.
 11. The system of claim 10,wherein high vacuum grease is arranged on the O-ring and the secondO-ring.
 12. The system of claim 10, wherein each of the O-ring and thesecond O-ring includes flourosilicone in order to reduce shrinkage ofthe each of the O-rings at a predetermined altitude.
 13. The system ofclaim 10, wherein the at least one groove and the second groove extendsaround a complete circumference of the plug member.
 14. The system ofclaim 10, wherein the at least one groove and the second groove arearranged parallel to one another on the plug member.
 15. The system ofclaim 10, wherein the at least one groove and the second groove arearranged below a first side of the flange and the tube extends above asecond side of the flange, the first side is opposite of the secondside.
 16. The system of claim 1, further comprising a fitting attachedto the first end, the fitting is configured for attachment to a fillingapparatus.
 17. The system of claim 16, wherein the fitting is brazewelded to the first end.
 18. The system of claim 1, wherein the fillingapparatus is configured for attachment to a top plate of a balloonenvelope such that the first end extends away from the balloon envelope.19. The system of claim 1, wherein each of the O-ring includesflourosilicone in order to reduce shrinkage of the each of the O-ringsat a predetermined altitude.
 20. The system of claim 10, wherein highvacuum grease is arranged on the O-ring.